1. Field of the Invention
The invention relates to a means for contact-free positional measurements on an electric/electronic or magnetic/electronic basis that is suitable for executing mechanically uninfluenced, electronically evaluatable positional measurements of a moving or resting part of the position indicator, particularly length measurements as well.
2. Description of the Prior Art
Known under the designation "differential transformers" are systems which measure the immersion depth of a core in a coil or a pair of coils as an electric signal which can be converted into length units over a calibration table. Differential transformers also function contact-free but have the disadvantage that the absolute quantity of the output signal--into which all environmental influences such as temperature, fluctuations of the electric parameters, distance of the ferrite from the coils, naturally enter--also has an influence on the precision of the length measurement. Given differential transformers, in particular, a precise electronic null balance that specifies the neutral position of the introduced ferrite between the coils is required. Thus, it is necessary to calibrate the transformers to determine the neutral position.